Retractable cord reels have been widely used in many applications, especially in telephonic applications. In some cord reels, the reel is spring biased so that the cord is under a constant tension when a length of cord is pulled from the reel, and automatically rewinds back onto the reel when tension is released. In other designs, the reel includes a catch or latching mechanism so that certain lengths of cord can be unwound from the reel and can be utilized without the withdrawn cord being under constant tension. Such reels also include a mechanism for automatically rewinding the cord back onto the reel when the device is no longer in use.
Many cord reels utilize a coil of flat flexible cable (FFC) as part of the data transmission circuit in the device (see e.g., U.S. Pat. No. 6,293,485 to Hollowed for one such reel design). Some forms of conventional FFC generally comprises a number of fine wires embedded within a polymeric matrix. Typically, the wires are laminated between one or more layers of a dielectric polymer sheet material, such as a polyester. Typically all of the wires are of the same size across the entire cable width. In other forms of FFC the wires are actually printed metallic traces (i.e., the FFC is a flexible printed circuit board).
Currently, FFC can be manufactured with a cable width and thickness suitable to meet USB 1.1 standards for data transmission but still fit within a relatively compact cord reel apparatus that can be conveniently mounted in, e.g., an airline seat back for use in conjunction with a telephone or game controller by passengers in flight. There is an increasing demand for corded devices that utilize a cord reel that meets USB 2.0, USB 3.0 or other standards for data and power transmission (i.e., battery charging). Cord reel designs that utilize a segment of FFC along with a conventional round-profile cord require splices from the FFC to round cord segments, which can lead to undesirable signal and power losses.
U.S. Pat. No. 3,695,544 to William J. Morey, Sr. describes a cord reel assembly that utilizes a single unitary round-profile cord, in which a majority of the cord is wound about a main cord storage compartment and a portion of the cord is wound in an adjacent disk-shaped take-up compartment having a thickness of approximately the diameter of the cord, so that the cord in the take-up compartment is constrained from flexing upward as the section of cord winds and unwinds. While this design does not include splices in the cord as in FFC-type reels, the configuration of the take-up compartment requires that the diameter of the cord reel assembly must be relatively large compared to the length of cord that can be withdrawn from the reel. The cord reel was designed for use with electrical appliances, machine tools and the like, and does not address the needs of modern electronic devices. Modern applications for cord reels often require a relatively small reel diameter relative to the desired necessary cord length that can be withdrawn from the reel, rendering the early unitary-cord reel design unsuitable for modern electronic data transfer applications.
There is an ongoing need for improved cord reel designs. The present application addresses this need.